Many prior art switching systems have used protection channels which can be switched in to bridge failed sections of normal operating channels. Typically, these prior systems have had data drop and insert capability for every single channel in the switching system and thus the master controller can merely check to see whether or not the protection channel for a given link is being used to bridge another failed channel before switching in the protection channel to bridge the most recently failed channel. If there are 20 terminals or sites including the end sites in a particular switching system, that means there are 19 possible sections of protection channel which may be used to bridge failed sections since each section would only involve the distance between adjacent serially connected drop and insert communication sites. The cost of the drop and insert circuitry for a channel which is not receiving or dropping information at a given site is much higher than the cost of a through-repeater which merely provides amplification of the signal on to the next site. It is thus desirable from a cost standpoint to be able to use through-repeaters on all channels which are not receiving or dropping information at a given site. This, however, introduces severe complications in providing protection to any failed section since the unit providing the switching must either know or find out what the length of the failed section is between drop and insert points for that channel and thus use that length of protection channel to bridge the failed section. An alternative is, of course, to switch the signal from the failed channel to a nonfailed channel.